The Effects Of Straw Application On Rice-rape Rotation System In Pingchang Country

Crop residues is an important biological resource in crop production system. Based on the questionnaire survey on Pingcang County, we found that a large number of crop stalks residues produced each year, but the majority of crop straw were discarded in the field, used as firewood or burned in situ, not only caused a serious waste of straw resources, but also polluted the environment. This research chooses four representative towns (Lingshan Town, white town, Jiang Kou Zhen) in Pingchang County, and, the system mode of rice-rape rotation, which was the most typical cultivation of the region as the research object, to research returning straw application.. Experiment with 3 treatments:no straw returning (CK), straw (JG), straw +rotten agent (JG+FSJ), and indexes including soil bulk density, organic matter, total nitrogen, total phosphorus, available phosphorus, total potassium, available potassium, slowly available K, pH, cation exchange capacity (CEC), rice and rape yield, and the organic carbon, total nitrogen, total phosphorus, total potassium content in crop straw. To analysis the effect of crop straw on soil physical and chemical properties, crop straw yield as well as organic carbon, nitrogen, phosphorus, potassium content. The main results are as follows:(1) Soil bulk density in JG, JG+FSJ decreased significantly, and the JG+FSJ, soil bulk density decreased more obviously. Compared with before the study, soil bulk density in CK treated remained unchanged, soil bulk density in JG, JG+FSJ treatment showed fluctuations, but the overall on a downward trend, and the decreased degree were the spring of 2013> fall 2012> spring 2012> fall 2011.(2) Not obvious changes of soil organic matter, slowly available K and CEC in JG, JG+FSJ. But on the whole, the soil organic matter and CEC had a tendency to increase, and soil slowly available K content decreased. Compared with CK, soil total nitrogen, total phosphorus, available phosphorus, total potassium, available potassium in JG, JG+FSJ increased, and straw effect was more obvious; soil pH value turned into a neutral range. From different years, soil organic matter, total P, available P, CEC, pH values in CK remained unchanged, total nitrogen, available phosphorus, total potassium, slowly available K decreased; In treatment of JG, JG+FSJ, slowly available K content had a the overall downward trend, other fertility index were increasing year after year, pH value close to neutral.(3) Compared with CK, the rice yield increased in JG, JG+FSJ treatment, but there were no significant difference. The rapeseed yield increased, and different treatment, production changed between different years, there were no consistent patterns.(4) Compared with CK, organic carbon and total potassium content of rice straw increased in JG, JG+FSJ treatment, and the changes of nitrogen and phosphorus content, were not obvious; organic carbon and nitrogen phosphorus and potassium content of rape straw increased significantly.To sum up, soil bulk density declined, soil fertility increased, crop yield and biomass increased continuously in straw returning, straw with fertilizer inoculants effect was more obvious.